/*
 * Copyright (c) 2012-2020 MIRACL UK Ltd.
 *
 * This file is part of MIRACL Core
 * (see https://github.com/miracl/core).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

//
//  aes.swift
//
//  Created by Michael Scott on 22/06/2015.
//  Copyright (c) 2015 Michael Scott. All rights reserved.
//
//   AES Encryption
//

public struct AES {
    var Nk:Int=0
    var Nr:Int=0
    var mode:Int=0;
    private var fkey=[UInt32](repeating: 0,count: 60)
    private var rkey=[UInt32](repeating: 0,count: 60)
    var f=[UInt8](repeating: 0,count: 16)

    public init() {}

    static public let ECB:Int=0
    static public let CBC:Int=1
    static public let CFB1:Int=2
    static public let CFB2:Int=3
    static public let CFB4:Int=5
    static public let OFB1:Int=14
    static public let OFB2:Int=15
    static public let OFB4:Int=17
    static public let OFB8:Int=21
    static public let OFB16:Int=29
    static public let CTR1:Int=30
    static public let CTR2:Int=31
    static public let CTR4:Int=33
    static public let CTR8:Int=37
    static public let CTR16:Int=45

    private static let InCo:[UInt8] = [ 0xB,0xD,0x9,0xE]  /* Inverse Coefficients */

    private static let ptab:[UInt8] =
    [ 1, 3, 5, 15, 17, 51, 85, 255, 26, 46, 114, 150, 161, 248, 19, 53,
     95, 225, 56, 72, 216, 115, 149, 164, 247, 2, 6, 10, 30, 34, 102, 170,
     229, 52, 92, 228, 55, 89, 235, 38, 106, 190, 217, 112, 144, 171, 230, 49,
     83, 245, 4, 12, 20, 60, 68, 204, 79, 209, 104, 184, 211, 110, 178, 205,
     76, 212, 103, 169, 224, 59, 77, 215, 98, 166, 241, 8, 24, 40, 120, 136,
     131, 158, 185, 208, 107, 189, 220, 127, 129, 152, 179, 206, 73, 219, 118, 154,
     181, 196, 87, 249, 16, 48, 80, 240, 11, 29, 39, 105, 187, 214, 97, 163,
     254, 25, 43, 125, 135, 146, 173, 236, 47, 113, 147, 174, 233, 32, 96, 160,
     251, 22, 58, 78, 210, 109, 183, 194, 93, 231, 50, 86, 250, 21, 63, 65,
     195, 94, 226, 61, 71, 201, 64, 192, 91, 237, 44, 116, 156, 191, 218, 117,
     159, 186, 213, 100, 172, 239, 42, 126, 130, 157, 188, 223, 122, 142, 137, 128,
     155, 182, 193, 88, 232, 35, 101, 175, 234, 37, 111, 177, 200, 67, 197, 84,
     252, 31, 33, 99, 165, 244, 7, 9, 27, 45, 119, 153, 176, 203, 70, 202,
     69, 207, 74, 222, 121, 139, 134, 145, 168, 227, 62, 66, 198, 81, 243, 14,
     18, 54, 90, 238, 41, 123, 141, 140, 143, 138, 133, 148, 167, 242, 13, 23,
     57, 75, 221, 124, 132, 151, 162, 253, 28, 36, 108, 180, 199, 82, 246, 1]

    private static let ltab:[UInt8] =
    [ 0, 255, 25, 1, 50, 2, 26, 198, 75, 199, 27, 104, 51, 238, 223, 3,
     100, 4, 224, 14, 52, 141, 129, 239, 76, 113, 8, 200, 248, 105, 28, 193,
     125, 194, 29, 181, 249, 185, 39, 106, 77, 228, 166, 114, 154, 201, 9, 120,
     101, 47, 138, 5, 33, 15, 225, 36, 18, 240, 130, 69, 53, 147, 218, 142,
     150, 143, 219, 189, 54, 208, 206, 148, 19, 92, 210, 241, 64, 70, 131, 56,
     102, 221, 253, 48, 191, 6, 139, 98, 179, 37, 226, 152, 34, 136, 145, 16,
     126, 110, 72, 195, 163, 182, 30, 66, 58, 107, 40, 84, 250, 133, 61, 186,
     43, 121, 10, 21, 155, 159, 94, 202, 78, 212, 172, 229, 243, 115, 167, 87,
     175, 88, 168, 80, 244, 234, 214, 116, 79, 174, 233, 213, 231, 230, 173, 232,
     44, 215, 117, 122, 235, 22, 11, 245, 89, 203, 95, 176, 156, 169, 81, 160,
     127, 12, 246, 111, 23, 196, 73, 236, 216, 67, 31, 45, 164, 118, 123, 183,
     204, 187, 62, 90, 251, 96, 177, 134, 59, 82, 161, 108, 170, 85, 41, 157,
     151, 178, 135, 144, 97, 190, 220, 252, 188, 149, 207, 205, 55, 63, 91, 209,
     83, 57, 132, 60, 65, 162, 109, 71, 20, 42, 158, 93, 86, 242, 211, 171,
     68, 17, 146, 217, 35, 32, 46, 137, 180, 124, 184, 38, 119, 153, 227, 165,
     103, 74, 237, 222, 197, 49, 254, 24, 13, 99, 140, 128, 192, 247, 112, 7]

    private static let fbsub:[UInt8] =
    [ 99, 124, 119, 123, 242, 107, 111, 197, 48, 1, 103, 43, 254, 215, 171, 118,
     202, 130, 201, 125, 250, 89, 71, 240, 173, 212, 162, 175, 156, 164, 114, 192,
     183, 253, 147, 38, 54, 63, 247, 204, 52, 165, 229, 241, 113, 216, 49, 21,
     4, 199, 35, 195, 24, 150, 5, 154, 7, 18, 128, 226, 235, 39, 178, 117,
     9, 131, 44, 26, 27, 110, 90, 160, 82, 59, 214, 179, 41, 227, 47, 132,
     83, 209, 0, 237, 32, 252, 177, 91, 106, 203, 190, 57, 74, 76, 88, 207,
     208, 239, 170, 251, 67, 77, 51, 133, 69, 249, 2, 127, 80, 60, 159, 168,
     81, 163, 64, 143, 146, 157, 56, 245, 188, 182, 218, 33, 16, 255, 243, 210,
     205, 12, 19, 236, 95, 151, 68, 23, 196, 167, 126, 61, 100, 93, 25, 115,
     96, 129, 79, 220, 34, 42, 144, 136, 70, 238, 184, 20, 222, 94, 11, 219,
     224, 50, 58, 10, 73, 6, 36, 92, 194, 211, 172, 98, 145, 149, 228, 121,
     231, 200, 55, 109, 141, 213, 78, 169, 108, 86, 244, 234, 101, 122, 174, 8,
     186, 120, 37, 46, 28, 166, 180, 198, 232, 221, 116, 31, 75, 189, 139, 138,
     112, 62, 181, 102, 72, 3, 246, 14, 97, 53, 87, 185, 134, 193, 29, 158,
     225, 248, 152, 17, 105, 217, 142, 148, 155, 30, 135, 233, 206, 85, 40, 223,
     140, 161, 137, 13, 191, 230, 66, 104, 65, 153, 45, 15, 176, 84, 187, 22]

    private static let rbsub:[UInt8] =
    [ 82, 9, 106, 213, 48, 54, 165, 56, 191, 64, 163, 158, 129, 243, 215, 251,
     124, 227, 57, 130, 155, 47, 255, 135, 52, 142, 67, 68, 196, 222, 233, 203,
     84, 123, 148, 50, 166, 194, 35, 61, 238, 76, 149, 11, 66, 250, 195, 78,
     8, 46, 161, 102, 40, 217, 36, 178, 118, 91, 162, 73, 109, 139, 209, 37,
     114, 248, 246, 100, 134, 104, 152, 22, 212, 164, 92, 204, 93, 101, 182, 146,
     108, 112, 72, 80, 253, 237, 185, 218, 94, 21, 70, 87, 167, 141, 157, 132,
     144, 216, 171, 0, 140, 188, 211, 10, 247, 228, 88, 5, 184, 179, 69, 6,
     208, 44, 30, 143, 202, 63, 15, 2, 193, 175, 189, 3, 1, 19, 138, 107,
     58, 145, 17, 65, 79, 103, 220, 234, 151, 242, 207, 206, 240, 180, 230, 115,
     150, 172, 116, 34, 231, 173, 53, 133, 226, 249, 55, 232, 28, 117, 223, 110,
     71, 241, 26, 113, 29, 41, 197, 137, 111, 183, 98, 14, 170, 24, 190, 27,
     252, 86, 62, 75, 198, 210, 121, 32, 154, 219, 192, 254, 120, 205, 90, 244,
     31, 221, 168, 51, 136, 7, 199, 49, 177, 18, 16, 89, 39, 128, 236, 95,
     96, 81, 127, 169, 25, 181, 74, 13, 45, 229, 122, 159, 147, 201, 156, 239,
     160, 224, 59, 77, 174, 42, 245, 176, 200, 235, 187, 60, 131, 83, 153, 97,
     23, 43, 4, 126, 186, 119, 214, 38, 225, 105, 20, 99, 85, 33, 12, 125]

    private static let rco:[UInt8] =
    [1,2,4,8,16,32,64,128,27,54,108,216,171,77,154,47]

    private static let ftable:[UInt32] =
    [0xa56363c6,0x847c7cf8,0x997777ee,0x8d7b7bf6,0xdf2f2ff,0xbd6b6bd6,
    0xb16f6fde,0x54c5c591,0x50303060,0x3010102,0xa96767ce,0x7d2b2b56,
    0x19fefee7,0x62d7d7b5,0xe6abab4d,0x9a7676ec,0x45caca8f,0x9d82821f,
    0x40c9c989,0x877d7dfa,0x15fafaef,0xeb5959b2,0xc947478e,0xbf0f0fb,
    0xecadad41,0x67d4d4b3,0xfda2a25f,0xeaafaf45,0xbf9c9c23,0xf7a4a453,
    0x967272e4,0x5bc0c09b,0xc2b7b775,0x1cfdfde1,0xae93933d,0x6a26264c,
    0x5a36366c,0x413f3f7e,0x2f7f7f5,0x4fcccc83,0x5c343468,0xf4a5a551,
    0x34e5e5d1,0x8f1f1f9,0x937171e2,0x73d8d8ab,0x53313162,0x3f15152a,
    0xc040408,0x52c7c795,0x65232346,0x5ec3c39d,0x28181830,0xa1969637,
    0xf05050a,0xb59a9a2f,0x907070e,0x36121224,0x9b80801b,0x3de2e2df,
    0x26ebebcd,0x6927274e,0xcdb2b27f,0x9f7575ea,0x1b090912,0x9e83831d,
    0x742c2c58,0x2e1a1a34,0x2d1b1b36,0xb26e6edc,0xee5a5ab4,0xfba0a05b,
    0xf65252a4,0x4d3b3b76,0x61d6d6b7,0xceb3b37d,0x7b292952,0x3ee3e3dd,
    0x712f2f5e,0x97848413,0xf55353a6,0x68d1d1b9,0x0,0x2cededc1,
    0x60202040,0x1ffcfce3,0xc8b1b179,0xed5b5bb6,0xbe6a6ad4,0x46cbcb8d,
    0xd9bebe67,0x4b393972,0xde4a4a94,0xd44c4c98,0xe85858b0,0x4acfcf85,
    0x6bd0d0bb,0x2aefefc5,0xe5aaaa4f,0x16fbfbed,0xc5434386,0xd74d4d9a,
    0x55333366,0x94858511,0xcf45458a,0x10f9f9e9,0x6020204,0x817f7ffe,
    0xf05050a0,0x443c3c78,0xba9f9f25,0xe3a8a84b,0xf35151a2,0xfea3a35d,
    0xc0404080,0x8a8f8f05,0xad92923f,0xbc9d9d21,0x48383870,0x4f5f5f1,
    0xdfbcbc63,0xc1b6b677,0x75dadaaf,0x63212142,0x30101020,0x1affffe5,
    0xef3f3fd,0x6dd2d2bf,0x4ccdcd81,0x140c0c18,0x35131326,0x2fececc3,
    0xe15f5fbe,0xa2979735,0xcc444488,0x3917172e,0x57c4c493,0xf2a7a755,
    0x827e7efc,0x473d3d7a,0xac6464c8,0xe75d5dba,0x2b191932,0x957373e6,
    0xa06060c0,0x98818119,0xd14f4f9e,0x7fdcdca3,0x66222244,0x7e2a2a54,
    0xab90903b,0x8388880b,0xca46468c,0x29eeeec7,0xd3b8b86b,0x3c141428,
    0x79dedea7,0xe25e5ebc,0x1d0b0b16,0x76dbdbad,0x3be0e0db,0x56323264,
    0x4e3a3a74,0x1e0a0a14,0xdb494992,0xa06060c,0x6c242448,0xe45c5cb8,
    0x5dc2c29f,0x6ed3d3bd,0xefacac43,0xa66262c4,0xa8919139,0xa4959531,
    0x37e4e4d3,0x8b7979f2,0x32e7e7d5,0x43c8c88b,0x5937376e,0xb76d6dda,
    0x8c8d8d01,0x64d5d5b1,0xd24e4e9c,0xe0a9a949,0xb46c6cd8,0xfa5656ac,
    0x7f4f4f3,0x25eaeacf,0xaf6565ca,0x8e7a7af4,0xe9aeae47,0x18080810,
    0xd5baba6f,0x887878f0,0x6f25254a,0x722e2e5c,0x241c1c38,0xf1a6a657,
    0xc7b4b473,0x51c6c697,0x23e8e8cb,0x7cdddda1,0x9c7474e8,0x211f1f3e,
    0xdd4b4b96,0xdcbdbd61,0x868b8b0d,0x858a8a0f,0x907070e0,0x423e3e7c,
    0xc4b5b571,0xaa6666cc,0xd8484890,0x5030306,0x1f6f6f7,0x120e0e1c,
    0xa36161c2,0x5f35356a,0xf95757ae,0xd0b9b969,0x91868617,0x58c1c199,
    0x271d1d3a,0xb99e9e27,0x38e1e1d9,0x13f8f8eb,0xb398982b,0x33111122,
    0xbb6969d2,0x70d9d9a9,0x898e8e07,0xa7949433,0xb69b9b2d,0x221e1e3c,
    0x92878715,0x20e9e9c9,0x49cece87,0xff5555aa,0x78282850,0x7adfdfa5,
    0x8f8c8c03,0xf8a1a159,0x80898909,0x170d0d1a,0xdabfbf65,0x31e6e6d7,
    0xc6424284,0xb86868d0,0xc3414182,0xb0999929,0x772d2d5a,0x110f0f1e,
    0xcbb0b07b,0xfc5454a8,0xd6bbbb6d,0x3a16162c]

    private static let rtable:[UInt32] =
    [0x50a7f451,0x5365417e,0xc3a4171a,0x965e273a,0xcb6bab3b,0xf1459d1f,
    0xab58faac,0x9303e34b,0x55fa3020,0xf66d76ad,0x9176cc88,0x254c02f5,
    0xfcd7e54f,0xd7cb2ac5,0x80443526,0x8fa362b5,0x495ab1de,0x671bba25,
    0x980eea45,0xe1c0fe5d,0x2752fc3,0x12f04c81,0xa397468d,0xc6f9d36b,
    0xe75f8f03,0x959c9215,0xeb7a6dbf,0xda595295,0x2d83bed4,0xd3217458,
    0x2969e049,0x44c8c98e,0x6a89c275,0x78798ef4,0x6b3e5899,0xdd71b927,
    0xb64fe1be,0x17ad88f0,0x66ac20c9,0xb43ace7d,0x184adf63,0x82311ae5,
    0x60335197,0x457f5362,0xe07764b1,0x84ae6bbb,0x1ca081fe,0x942b08f9,
    0x58684870,0x19fd458f,0x876cde94,0xb7f87b52,0x23d373ab,0xe2024b72,
    0x578f1fe3,0x2aab5566,0x728ebb2,0x3c2b52f,0x9a7bc586,0xa50837d3,
    0xf2872830,0xb2a5bf23,0xba6a0302,0x5c8216ed,0x2b1ccf8a,0x92b479a7,
    0xf0f207f3,0xa1e2694e,0xcdf4da65,0xd5be0506,0x1f6234d1,0x8afea6c4,
    0x9d532e34,0xa055f3a2,0x32e18a05,0x75ebf6a4,0x39ec830b,0xaaef6040,
    0x69f715e,0x51106ebd,0xf98a213e,0x3d06dd96,0xae053edd,0x46bde64d,
    0xb58d5491,0x55dc471,0x6fd40604,0xff155060,0x24fb9819,0x97e9bdd6,
    0xcc434089,0x779ed967,0xbd42e8b0,0x888b8907,0x385b19e7,0xdbeec879,
    0x470a7ca1,0xe90f427c,0xc91e84f8,0x0,0x83868009,0x48ed2b32,
    0xac70111e,0x4e725a6c,0xfbff0efd,0x5638850f,0x1ed5ae3d,0x27392d36,
    0x64d90f0a,0x21a65c68,0xd1545b9b,0x3a2e3624,0xb1670a0c,0xfe75793,
    0xd296eeb4,0x9e919b1b,0x4fc5c080,0xa220dc61,0x694b775a,0x161a121c,
    0xaba93e2,0xe52aa0c0,0x43e0223c,0x1d171b12,0xb0d090e,0xadc78bf2,
    0xb9a8b62d,0xc8a91e14,0x8519f157,0x4c0775af,0xbbdd99ee,0xfd607fa3,
    0x9f2601f7,0xbcf5725c,0xc53b6644,0x347efb5b,0x7629438b,0xdcc623cb,
    0x68fcedb6,0x63f1e4b8,0xcadc31d7,0x10856342,0x40229713,0x2011c684,
    0x7d244a85,0xf83dbbd2,0x1132f9ae,0x6da129c7,0x4b2f9e1d,0xf330b2dc,
    0xec52860d,0xd0e3c177,0x6c16b32b,0x99b970a9,0xfa489411,0x2264e947,
    0xc48cfca8,0x1a3ff0a0,0xd82c7d56,0xef903322,0xc74e4987,0xc1d138d9,
    0xfea2ca8c,0x360bd498,0xcf81f5a6,0x28de7aa5,0x268eb7da,0xa4bfad3f,
    0xe49d3a2c,0xd927850,0x9bcc5f6a,0x62467e54,0xc2138df6,0xe8b8d890,
    0x5ef7392e,0xf5afc382,0xbe805d9f,0x7c93d069,0xa92dd56f,0xb31225cf,
    0x3b99acc8,0xa77d1810,0x6e639ce8,0x7bbb3bdb,0x97826cd,0xf418596e,
    0x1b79aec,0xa89a4f83,0x656e95e6,0x7ee6ffaa,0x8cfbc21,0xe6e815ef,
    0xd99be7ba,0xce366f4a,0xd4099fea,0xd67cb029,0xafb2a431,0x31233f2a,
    0x3094a5c6,0xc066a235,0x37bc4e74,0xa6ca82fc,0xb0d090e0,0x15d8a733,
    0x4a9804f1,0xf7daec41,0xe50cd7f,0x2ff69117,0x8dd64d76,0x4db0ef43,
    0x544daacc,0xdf0496e4,0xe3b5d19e,0x1b886a4c,0xb81f2cc1,0x7f516546,
    0x4ea5e9d,0x5d358c01,0x737487fa,0x2e410bfb,0x5a1d67b3,0x52d2db92,
    0x335610e9,0x1347d66d,0x8c61d79a,0x7a0ca137,0x8e14f859,0x893c13eb,
    0xee27a9ce,0x35c961b7,0xede51ce1,0x3cb1477a,0x59dfd29c,0x3f73f255,
    0x79ce1418,0xbf37c773,0xeacdf753,0x5baafd5f,0x146f3ddf,0x86db4478,
    0x81f3afca,0x3ec468b9,0x2c342438,0x5f40a3c2,0x72c31d16,0xc25e2bc,
    0x8b493c28,0x41950dff,0x7101a839,0xdeb30c08,0x9ce4b4d8,0x90c15664,
    0x6184cb7b,0x70b632d5,0x745c6c48,0x4257b8d0]

    /* Rotates 32-bit word left by 1, 2 or 3 byte  */

    private static func ROTL8(_ x: UInt32) -> UInt32
    {
        return (((x)<<8)|((x)>>24))
    }

    private static func ROTL16(_ x: UInt32) -> UInt32
    {
        return (((x)<<16)|((x)>>16))
    }

    private static func ROTL24(_ x: UInt32) -> UInt32
    {
        return (((x)<<24)|((x)>>8))
    }

    private static func pack(_ b: [UInt8]) -> UInt32
    { /* pack bytes into a 32-bit Word */
        var r=((UInt32(b[3])&0xff)<<24)|((UInt32(b[2])&0xff)<<16)
        r = r|((UInt32(b[1])&0xff)<<8)|(UInt32(b[0])&0xff)
        return r
    }

    private static func unpack(_ a: UInt32) -> [UInt8]
    { /* unpack bytes from a word */
        let b:[UInt8]=[UInt8(a&0xff),UInt8((a>>8)&0xff),UInt8((a>>16)&0xff),UInt8((a>>24)&0xff)];
        return b;
    }

    private static func bmul(_ x: UInt8,_ y:UInt8) -> UInt8
    { /* x.y= AntiLog(Log(x) + Log(y)) */

        let ix=Int(x)&0xff
        let iy=Int(y)&0xff
        let lx=Int(ltab[ix])&0xff
        let ly=Int(ltab[iy])&0xff

        if x != 0 && y != 0 {return ptab[(lx+ly)%255]}
        else {return UInt8(0)}
    }

    private static func SubByte(_ a: UInt32) -> UInt32
    {
        var b=unpack(a)
        b[0]=fbsub[Int(b[0])]
        b[1]=fbsub[Int(b[1])]
        b[2]=fbsub[Int(b[2])]
        b[3]=fbsub[Int(b[3])]
        return pack(b);
    }

    private static func product(_ x: UInt32,_ y: UInt32) -> UInt8
    { /* dot product of two 4-byte arrays */
        let xb=unpack(x);
        let yb=unpack(y);

        return (bmul(xb[0],yb[0])^bmul(xb[1],yb[1])^bmul(xb[2],yb[2])^bmul(xb[3],yb[3]))
    }

    private static func InvMixCol(_ x: UInt32) -> UInt32
    { /* matrix Multiplication */
        var b=[UInt8](repeating: 0,count: 4)
        var m=pack(InCo);
        b[3]=product(m,x);
        m=ROTL24(m);
        b[2]=product(m,x);
        m=ROTL24(m);
        b[1]=product(m,x);
        m=ROTL24(m);
        b[0]=product(m,x);
        let y=pack(b)
        return y
    }

    private static func increment(_ f:inout [UInt8])
    {
        for i in 0 ..< 16
        {
            f[i]+=1
            if f[i] != 0 {break}
        }
    }

    /* reset cipher */
    public mutating func reset(_ m: Int,_ iv:[UInt8]?)
    { /* reset mode, or reset iv */
        mode=m;
        for i in 0 ..< 16 {f[i]=0}
        if (mode != AES.ECB) && (iv != nil)
            {for i in 0 ..< 16 {f[i]=iv![i]}} /*??*/
    }

    @discardableResult public mutating func init_it(_ m:Int,_ nkey:Int, _ key:[UInt8],_ iv:[UInt8]?) -> Bool
    {   /* Key=16 bytes */
        /* Key Scheduler. Create expanded encryption key */
        var CipherKey=[UInt32](repeating: 0,count: 8)
        var b=[UInt8](repeating: 0,count: 4)
        let nk=nkey/4
        if nk != 4 && nk != 6 && nk != 8 {
            return false
        }
	let nr=6+nk
	Nk=nk; Nr=nr;

	reset(m,iv);
        let N=4*(nr+1)

        var j=0
        for  i in 0 ..< nk
        {
            for k in 0 ..< 4 {b[k]=key[j+k]}
            CipherKey[i]=AES.pack(b);
            j+=4;
        }
        for i in 0 ..< nk {fkey[i]=CipherKey[i]}
        j=nk
        var k=0
        while j<N
        {
            fkey[j]=fkey[j-nk]^AES.SubByte(AES.ROTL24(fkey[j-1]))^UInt32(AES.rco[k])
	    if nk <= 6 {
                var i=1
                while i<nk && (i+j)<N
                {
                    fkey[i+j]=fkey[i+j-nk]^fkey[i+j-1]
                    i+=1
		}
            } else {
                var i=1
                while i<4 && (i+j)<N
                {
                    fkey[i+j]=fkey[i+j-nk]^fkey[i+j-1]
                    i+=1
		}
                if (j+4) < N {
		    fkey[j + 4] = fkey[j + 4 - nk] ^ AES.SubByte(fkey[j + 3])
		}
		i=5
                while i<nk && (i+j)<N
		{
		    fkey[i + j] = fkey[i + j - nk] ^ fkey[i + j - 1]
		    i+=1
		}
	    }
            j+=nk
            k+=1
        }

        /* now for the expanded decrypt key in reverse order */

        for j in 0 ..< 4 {rkey[j+N-4]=fkey[j]}
        var i=4
        while i<N-4
        {
            let k=N-4-i;
            for j in 0 ..< 4 {rkey[k+j]=AES.InvMixCol(fkey[i+j])}
            i+=4
        }
        for j in N-4 ..< N {rkey[j-N+4]=fkey[j]}
	   return true
    }

    func getreg() -> [UInt8]
    {
        var ir=[UInt8](repeating: 0,count: 16)
        for i in 0 ..< 16 {ir[i]=f[i]}
        return ir;
    }

    /* Encrypt a single block */
    func ecb_encrypt(_ buff:inout [UInt8])
    {
        var b=[UInt8](repeating: 0,count: 4)
        var p=[UInt32](repeating: 0,count: 4)
        var q=[UInt32](repeating: 0,count: 4)

        var j=0
        for i in 0 ..< 4
        {
            for k in 0 ..< 4 {b[k]=buff[j+k]}
            p[i]=AES.pack(b);
            p[i]^=fkey[i];
            j+=4
        }

        var k=4;

    /* State alternates between p and q */
        for _ in 1 ..< Nr
        {
            q[0]=fkey[k]^AES.ftable[Int(p[0]&0xff)]^AES.ROTL8(AES.ftable[Int((p[1]>>8)&0xff)])^AES.ROTL16(AES.ftable[Int((p[2]>>16)&0xff)])^AES.ROTL24(AES.ftable[Int((p[3]>>24)&0xff)])

            q[1]=fkey[k+1]^AES.ftable[Int(p[1]&0xff)]^AES.ROTL8(AES.ftable[Int((p[2]>>8)&0xff)])^AES.ROTL16(AES.ftable[Int((p[3]>>16)&0xff)])^AES.ROTL24(AES.ftable[Int((p[0]>>24)&0xff)])

            q[2]=fkey[k+2]^AES.ftable[Int(p[2]&0xff)]^AES.ROTL8(AES.ftable[Int((p[3]>>8)&0xff)])^AES.ROTL16(AES.ftable[Int((p[0]>>16)&0xff)])^AES.ROTL24(AES.ftable[Int((p[1]>>24)&0xff)])

            q[3]=fkey[k+3]^AES.ftable[Int(p[3]&0xff)]^AES.ROTL8(AES.ftable[Int((p[0]>>8)&0xff)])^AES.ROTL16(AES.ftable[Int((p[1]>>16)&0xff)])^AES.ROTL24(AES.ftable[Int((p[2]>>24)&0xff)])

            k+=4;
            for j in 0 ..< 4
            {
				let t=p[j]; p[j]=q[j]; q[j]=t;
            }
        }

    /* Last Round */

        q[0]=fkey[k]^UInt32(AES.fbsub[Int(p[0]&0xff)])^AES.ROTL8(UInt32(AES.fbsub[Int((p[1]>>8)&0xff)]))^AES.ROTL16(UInt32(AES.fbsub[Int((p[2]>>16)&0xff)]))^AES.ROTL24(UInt32(AES.fbsub[Int((p[3]>>24)&0xff)]))

        q[1]=fkey[k+1]^UInt32(AES.fbsub[Int(p[1]&0xff)])^AES.ROTL8(UInt32(AES.fbsub[Int((p[2]>>8)&0xff)]))^AES.ROTL16(UInt32(AES.fbsub[Int((p[3]>>16)&0xff)]))^AES.ROTL24(UInt32(AES.fbsub[Int((p[0]>>24)&0xff)]))

        q[2]=fkey[k+2]^UInt32(AES.fbsub[Int(p[2]&0xff)])^AES.ROTL8(UInt32(AES.fbsub[Int((p[3]>>8)&0xff)]))^AES.ROTL16(UInt32(AES.fbsub[Int((p[0]>>16)&0xff)]))^AES.ROTL24(UInt32(AES.fbsub[Int((p[1]>>24)&0xff)]))

        q[3]=fkey[k+3]^UInt32(AES.fbsub[Int((p[3])&0xff)])^AES.ROTL8(UInt32(AES.fbsub[Int((p[0]>>8)&0xff)]))^AES.ROTL16(UInt32(AES.fbsub[Int((p[1]>>16)&0xff)]))^AES.ROTL24(UInt32(AES.fbsub[Int((p[2]>>24)&0xff)]))

        j=0
        for i in 0 ..< 4
        {
            b=AES.unpack(q[i])
            for k in 0 ..< 4 {buff[j+k]=b[k]}
            j+=4
        }
    }

    /* Decrypt a single block */
    func ecb_decrypt(_ buff:inout [UInt8])
    {
        var b=[UInt8](repeating: 0,count: 4)
        var p=[UInt32](repeating: 0,count: 4)
        var q=[UInt32](repeating: 0,count: 4)

        var j=0
        for i in 0 ..< 4
        {
            for k in 0 ..< 4 {b[k]=buff[j+k]}
            p[i]=AES.pack(b);
            p[i]^=rkey[i];
            j+=4
        }

        var k=4

    /* State alternates between p and q */
        for _ in 1 ..< Nr
        {

            q[0]=rkey[k]^AES.rtable[Int(p[0]&0xff)]^AES.ROTL8(AES.rtable[Int((p[3]>>8)&0xff)])^AES.ROTL16(AES.rtable[Int((p[2]>>16)&0xff)])^AES.ROTL24(AES.rtable[Int((p[1]>>24)&0xff)])

            q[1]=rkey[k+1]^AES.rtable[Int(p[1]&0xff)]^AES.ROTL8(AES.rtable[Int((p[0]>>8)&0xff)])^AES.ROTL16(AES.rtable[Int((p[3]>>16)&0xff)])^AES.ROTL24(AES.rtable[Int((p[2]>>24)&0xff)])


            q[2]=rkey[k+2]^AES.rtable[Int(p[2]&0xff)]^AES.ROTL8(AES.rtable[Int((p[1]>>8)&0xff)])^AES.ROTL16(AES.rtable[Int((p[0]>>16)&0xff)])^AES.ROTL24(AES.rtable[Int((p[3]>>24)&0xff)])

            q[3]=rkey[k+3]^AES.rtable[Int(p[3]&0xff)]^AES.ROTL8(AES.rtable[Int((p[2]>>8)&0xff)])^AES.ROTL16(AES.rtable[Int((p[1]>>16)&0xff)])^AES.ROTL24(AES.rtable[Int((p[0]>>24)&0xff)])


            k+=4;
            for j in 0 ..< 4
            {
				let t=p[j]; p[j]=q[j]; q[j]=t;
            }
        }

    /* Last Round */

        q[0]=rkey[k]^UInt32(AES.rbsub[Int(p[0]&0xff)])^AES.ROTL8(UInt32(AES.rbsub[Int((p[3]>>8)&0xff)]))^AES.ROTL16(UInt32(AES.rbsub[Int((p[2]>>16)&0xff)]))^AES.ROTL24(UInt32(AES.rbsub[Int((p[1]>>24)&0xff)]))

        q[1]=rkey[k+1]^UInt32(AES.rbsub[Int(p[1]&0xff)])^AES.ROTL8(UInt32(AES.rbsub[Int((p[0]>>8)&0xff)]))^AES.ROTL16(UInt32(AES.rbsub[Int((p[3]>>16)&0xff)]))^AES.ROTL24(UInt32(AES.rbsub[Int((p[2]>>24)&0xff)]))


        q[2]=rkey[k+2]^UInt32(AES.rbsub[Int(p[2]&0xff)])^AES.ROTL8(UInt32(AES.rbsub[Int((p[1]>>8)&0xff)]))^AES.ROTL16(UInt32(AES.rbsub[Int((p[0]>>16)&0xff)]))^AES.ROTL24(UInt32(AES.rbsub[Int((p[3]>>24)&0xff)]))

        q[3]=rkey[k+3]^UInt32(AES.rbsub[Int((p[3])&0xff)])^AES.ROTL8(UInt32(AES.rbsub[Int((p[2]>>8)&0xff)]))^AES.ROTL16(UInt32(AES.rbsub[Int((p[1]>>16)&0xff)]))^AES.ROTL24(UInt32(AES.rbsub[Int((p[0]>>24)&0xff)]))

        j=0
        for i in 0 ..< 4
        {
            b=AES.unpack(q[i]);
            for k in 0 ..< 4 {buff[j+k]=b[k]}
            j+=4
        }
    }

    /* Encrypt using selected mode of operation */
    @discardableResult public mutating func encrypt(_ buff:inout [UInt8]) -> UInt32
    {
        var st=[UInt8](repeating: 0,count: 16)

    // Supported Modes of Operation

        var fell_off:UInt32=0;
        switch (mode)
        {
        case AES.ECB:
            ecb_encrypt(&buff)
            return 0
        case AES.CBC:
            for j in 0 ..< 16 {buff[j]^=f[j]}
            ecb_encrypt(&buff);
            for j in 0 ..< 16 {f[j]=buff[j]}
            return 0;

        case AES.CFB1:
            fallthrough
        case AES.CFB2:
            fallthrough
        case AES.CFB4:
            let bytes=mode-AES.CFB1+1
            for j in 0 ..< bytes {fell_off=(fell_off<<8)|UInt32(f[j])}
            for j in 0 ..< 16 {st[j]=f[j]}
            for j in bytes ..< 16 {f[j-bytes]=f[j]}
            ecb_encrypt(&st);
            for j in 0 ..< bytes
            {
				buff[j]^=st[j];
				f[16-bytes+j]=buff[j];
            }
            return fell_off;

        case AES.OFB1:
            fallthrough
        case AES.OFB2:
            fallthrough
        case AES.OFB4:
            fallthrough
        case AES.OFB8:
            fallthrough
        case AES.OFB16:

            let bytes=mode-AES.OFB1+1
            ecb_encrypt(&f)
            for j in 0 ..< bytes {buff[j]^=f[j]}
            return 0;

        case AES.CTR1:
            fallthrough
        case AES.CTR2:
            fallthrough
        case AES.CTR4:
            fallthrough
        case AES.CTR8:
            fallthrough
        case AES.CTR16:
            let bytes=mode-AES.CTR1+1
            for j in 0 ..< 16 {st[j]=f[j]}
            ecb_encrypt(&st)
            for j in 0 ..< bytes {buff[j]^=st[j]}
            AES.increment(&f)
            return 0

        default:
            return 0;
        }
    }

    /* Decrypt using selected mode of operation */
    @discardableResult public mutating func decrypt(_ buff:inout [UInt8]) -> UInt32
    {

        var st=[UInt8](repeating: 0,count: 16)

        // Supported Modes of Operation

        var fell_off:UInt32=0;
        switch (mode)
        {
        case AES.ECB:
            ecb_decrypt(&buff);
            return 0;
        case AES.CBC:
            for j in 0 ..< 16
            {
				st[j]=f[j];
				f[j]=buff[j];
            }
            ecb_decrypt(&buff);
            for j in 0 ..< 16
            {
				buff[j]^=st[j];
				st[j]=0;
            }
            return 0;
        case AES.CFB1:
            fallthrough
        case AES.CFB2:
            fallthrough
        case AES.CFB4:
            let bytes=mode-AES.CFB1+1;
            for j in 0 ..< bytes {fell_off=(fell_off<<8)|UInt32(f[j])}
            for j in 0 ..< 16 {st[j]=f[j]}
            for j in bytes ..< 16 {f[j-bytes]=f[j]}
            ecb_encrypt(&st);
            for j in 0 ..< bytes
            {
				f[16-bytes+j]=buff[j]
				buff[j]^=st[j]
            }
            return fell_off
        case AES.OFB1:
            fallthrough
        case AES.OFB2:
            fallthrough
        case AES.OFB4:
            fallthrough
        case AES.OFB8:
            fallthrough
        case AES.OFB16:
            let bytes=mode-AES.OFB1+1
            ecb_encrypt(&f);
            for j in 0 ..< bytes {buff[j]^=f[j]}
            return 0;

        case AES.CTR1:
            fallthrough
        case AES.CTR2:
            fallthrough
        case AES.CTR4:
            fallthrough
        case AES.CTR8:
            fallthrough
        case AES.CTR16:
            let bytes=mode-AES.CTR1+1
            for j in 0 ..< 16 {st[j]=f[j]}
            ecb_encrypt(&st)
            for j in 0 ..< bytes {buff[j]^=st[j]}
            AES.increment(&f)
            return 0

        default:
            return 0;
        }
    }

    /* Clean up and delete left-overs */
    public mutating func end()
    { // clean up
        for i in 0 ..< 4*(Nr+1)
            {fkey[i]=0; rkey[i]=0}
        for i in 0 ..< 16
            {f[i]=0}
    }

    /* AES encryption/decryption. Encrypt byte array M using key K and returns ciphertext */
    static public func CBC_IV0_ENCRYPT(_ K:[UInt8],_ M:[UInt8]) -> [UInt8]
    { /* AES CBC encryption, with Null IV and key K */
    /* Input is from an octet string M, output is to an octet string C */
    /* Input is padded as necessary to make up a full final block */
        var a=AES();
        var buff=[UInt8](repeating: 0,count: 16)
        let clen=16+(M.count/16)*16;

        var C=[UInt8](repeating: 0,count: clen)

        a.init_it(AES.CBC,K.count,K,nil)

        var ipt=0; var opt=0;
        var fin=false;
        var i:Int=0
        while true
        {
            i=0
            while i<16
            {
                if (ipt<M.count) {buff[i]=M[ipt]; ipt+=1}
                else {fin=true; break;}
                i+=1
            }
            if fin {break}
            a.encrypt(&buff);
            for j in 0 ..< 16
                {C[opt]=buff[j]; opt+=1}
        }

    /* last block, filled up to i-th index */

        let padlen=16-i;
        for j in i ..< 16 {buff[j]=UInt8(padlen&0xff)}

        a.encrypt(&buff);

        for j in 0 ..< 16
            {C[opt]=buff[j]; opt+=1}
        a.end();
        return C;
    }

    /* returns plaintext if all consistent, else returns null string */
    static public func CBC_IV0_DECRYPT(_ K:[UInt8],_ C:[UInt8]) -> [UInt8]
    { /* padding is removed */
        var a=AES();

        var buff=[UInt8](repeating: 0,count: 16)
        var MM=[UInt8](repeating: 0,count: C.count)

        var ipt=0; var opt=0;

        a.init_it(AES.CBC,K.count,K,nil);

        if C.count==0 {return [UInt8]()}
        var ch=C[ipt]; ipt+=1

        var fin=false;
        var i:Int=0
        while true
        {
            i=0
            while i<16
            {
                buff[i]=ch;
                if ipt>=C.count {fin=true; break;}
                else {ch=C[ipt]; ipt+=1}
                i+=1
            }
            a.decrypt(&buff);
            if fin {break}
            for j in 0 ..< 16
                {MM[opt]=buff[j]; opt+=1}
        }

        a.end();
        var bad=false;
        let padlen:Int=Int(buff[15]);
        if i != 15 || padlen<1 || padlen>16 {bad=true}
        if padlen>=2 && padlen<=16
        {
            for j in 16-padlen ..< 16 {if buff[j] != buff[15] {bad=true}}
        }
        if !bad
        {
            for j in 0 ..< 16-padlen
                {MM[opt]=buff[j]; opt+=1}
        }

        if bad {return [UInt8]()}

        var M=[UInt8](repeating: 0,count: opt)
        for j in 0 ..< opt {M[j]=MM[j]}

        return M;
    }


}
